How to save array of tuples in UserDefaults

Question

I am using a tuple of arrays in one of my files and want to start saving it in UserDefaults. Here is how I am storing my current data:

typealias savemytuple = (Name: String, NameID: String, BookID: String, Picture: NSData)
var savefun = [savemytuple]()

I have researched and found I may need to do something with the following for saving:

NSKeyedArchiver.archivedDataWithRootObject

And this for retrieving:

NSKeyedUnarchiver.unarchiveObjectWithData

Not sure if this way will work as my tuple has multiple data types. Any idea on how to do this?

Answer 1

The values in UserDefaults must be property lists, so you need to convert each tuple to a property list. A Data is a property list, and there are several ways to convert things to Data.

One way is to stop using a tuple and use a struct instead. If all of the struct's stored properties conform to Codable, then you can ask Swift to generate everything needed to make the struct itself conform to Codable just by declaring the conformance. Both String and Data conform to Codable.

Once the struct is Codable, you can convert one of them, or even an array of them, into a property list via JSONEncoder or PropertyListEncoder:

import Foundation

struct Bookie: Codable {
    var name: String
    var nameId: String
    var bookId: String
    var picture: Data
}

let bookies = [
    Bookie(name: "mbro12", nameId: "id1", bookId: "b1", picture: Data()),
    Bookie(name: "mayoff", nameId: "id2", bookId: "b2", picture: Data())
]
let bookiesData = try! PropertyListEncoder().encode(bookies)
UserDefaults.standard.set(bookiesData, forKey: "bookies")

let fetchedData = UserDefaults.standard.data(forKey: "bookies")!
let fetchedBookies = try! PropertyListDecoder().decode([Bookie].self, from: fetchedData)
print(fetchedBookies)